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Title: The antibacterial activity of tea infusions and their effect against the hospital pathogen clostridium difficile
Author: McCully, William Francis
ISNI:       0000 0004 2752 2108
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2013
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Clostridium difficile is one of the UK’s most common hospital acquired infections and there is anecdotal evidence to suggest that the bacteria are sensitive to the antibacterial properties of tea. Surprisingly, little research has been undertaken to characterise the inhibitory activity of aqueous tea infusions that are representative of traditional drinking habits. The antibacterial properties of tea are thought to be due to a group of polyphenols called catechins. However, their contribution to the inhibitory activity of tea infusions and their mechanism of action is still subject to debate. An antimicrobial assay, developed using Staphylococcus aureus as a model organism, was used to determine the antibacterial activity of a range of tea infusions against 75 clinical isolates of C. difficile that represented all the major strain ribotypes over 11 years. Green teas demonstrated more potent antibacterial activity than black teas and their activity was positively correlated with antioxidant power, hydrogen peroxide production, and catechin content. Furthermore, the country of origin of the tea affected the catechin content and subsequent antimicrobial activity of the infusion. Detailed chemical analysis using high performance liquid chromatography and counter current chromatography suggests that the antibacterial activity of tea is probably the result of synergistic interactions between a number of catechins rather than the activity of an individual compound. With regards to the mode of action by which tea inhibits C. difficile, electron microscopy studies of the bacterium treated with green tea revealed distinct changes to the outer cell structures of the bacteria. These changes were indicative of cell membrane blebbing, thus supporting the theory that tea compounds interact with the bacterial membrane and/or cell wall. Overall, this investigation concluded that tea infusions have inhibitory activity against C. difficile in vitro and may be useful in the treatment or prevention of C. difficile infections in vivo.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Q Science (General) ; RM Therapeutics. Pharmacology